Commonwealth Bank has defended its decision to pursue growth in personal lending and credit cards at a time when the economy is slowing down and there is a prospect that rising arrears rates will expose the bank to higher risk.The combined CBA and Bankwest credit card market share rose from 23.5 to 24.3 per cent in the year to June, and their other household lending share rose from 16.4 to 16.9 per cent over the same period. According to Australian Prudential Regulation Authority figures, CBA increased the size of its credit card book by 20.4 per cent over the two years to June. The APRA data shows that most banks have reduced their credit card outstandings over that period.CBA chief financial officer David Craig said: "We took a view two years ago that credit conditions were improving. We have picked up 130 basis points of market share in credit cards since and we have had similar growth in personal loans."However, the bank's personal loan and credit card arrears (payments past due 90 days or more) have picked up in the past six months.Craig said the bank's view was that the recent increase in arrears was seasonal. He said that, despite the recent rise, CBA's consumer credit arrears rate was below the industry average and was down year-on-year.The bank's view is that the additional risk of increasing consumer lending is justified by the high margin available on the business.One area of consumer lending not doing well is margin lending. CBA said its profit from its "equities and margin lending" unit fell 12 per cent. This was a major drag on the profit from business and private banking.